1. Field of the Invention
This invention relates to a taper angle setting and displaying method for a programming unit in which machining configurations are defined on a display unit (such as a cathode ray tube) and machining programs are automatically outputted according to the machining configurations thus defined.
2. Prior Art
A conventional method of displaying machining loci for a programming unit will be described with reference to FIGS. 5 through 8.
In FIG. 5, reference character L1 designates a machining locus extended from a machining start point P1, and L2 through L5, machining loci along a machining configuration. FIGS. 6(a) to 6(d) are top view, side view, front view, and perspective view of a tapered object formed by machining a workpiece according to the machining method shown in FIG. 5, respectively. FIG. 7 is a flow chart showing a conventional method of specifying taper angles. FIG. 8 shows a part of a program including machining data in formation of the tapered object shown in FIG. 6. The program additionally includes taper specifying data.
In order to form a machining program for machining a workpiece into a tapered object as shown in FIG. 6, the elements such as points, lines and circles forming the contour of the upper or lower surface of the tapered object are defined (Step 40), and thereafter machining paths are defined in the order of the machining loci L1 through L5 starting from the machining start point P1 (Step 41). The above-described operations have formed, a program for straightly machining the workpiece. However, in the case where the workpiece is to be machined into a tapered object as shown in FIG. 6, it is necessary to add taper data. In general, it is not always possible to apply one and the same taper data to all of the elements of the machining contour; that is, different elements generally have different taper angles. Accordingly, in the program, it is necessary to define a taper angle for every machining path. In addition, in the program, a taper angle must be defined with a positive sign or negative sign in accordance with the direction of the taper angle. That is, in a taper angle specifying method for a numerical control device, when a taper is inclined left with respect to the machining direction, the taper angle is provided with the negative sign, and when inclined right, the taper angle is provided with the positive sign. (In some numerical control devices, a positive taper angle is given at all times, and the sign is selected using NC code (such as G code).
Accordingly, for each element, a taper angle provided for each element by taking a taper inclination into account is inserted in the definition of a machining path (Step 42). The program thus formed is as shown in FIG. 8. After the elements, such as P1, L1 and L2, of the machining contour have been defined, the machining elements P1, L1, L2, etc. are inputted according to the machining direction, and then taper specifying data, namely, taper angle data are inserted between the elements thus inputted.
The machining-direction-indicating arrows are indicated on the machining paths L1 through L5 in FIG. 5; however, in practice they are not displayed.
The conventional method of setting and displaying taper angles for a programming unit is as described above. That is, after a machining direction has been determined, a taper angle must be determined (with a positive or negative sign) by taking the machining direction into account. Therefore, even in the case where, although the machining configuration is the same, the machining direction is opposite, it is necessary to set taper angles for all the machining loci again. This means that it is necessary to provide two machining programs; a program for forward machining, and a program for reverse machining, thus greatly lowering the work efficiency of the numerical control device. Furthermore, in the conventional method, although the machining loci are displayed, the taper specifying data for the machining elements are not displayed. That is, the taper specifying data (taper angle and taper direction) cannot be confirmed on the display screen.